1. Field of the Invention
The present invention generally relates to a powered, mobile concrete mixer having a mixing drum constructed of high density crosslink polyethylene plastic material. The drum includes a bottom supported by a conventional rigid metal pan secured to the external surface thereof to rigidify the plastic drum and extend the life expectancy of the mixer. A paddle assembly is positioned interiorly of the drum and is oriented to obtain minimum splashing during the mixing operation. A rigid metal ring gear is attached peripherally of the drum in spaced relation to the metal supporting pan with the ring gear and metal bottom pan being uniquely related to facilitate assembly and disassembly of the components for easy replacement of the components.
2. Description of the Prior Art
Concrete mixers of the type utilizing a generally vertically or angularly disposed mixing drum driven about a longitudinal axis with a paddle assembly mounted interiorly of the drum are well known. The drum includes a rigid peripheral ring gear mounted peripherally of the drum above the closed bottom end and below an open top end for rotating the drum about a generally longitudinal axis. The drum is supported from a frame by a yoke pivotally supported from the frame and a cradle assembly to enable pivotal movement of the drum from a generally vertical position to a tilted position with the open end of the drum being disposed below the pivotal axis of the drum to dump mixed concrete from the drum. A manually operated wheel or handle structure is associated with the yoke and frame to manually pivot the drum between a mixing position and a dumping position.
Concrete mixers as described above in which the drum is constructed of metal have been used for many years. In view of developments in plastic materials, recent efforts have been made to utilize a mixing drum constructed of plastic material in lieu of a metal mixing drum. High density crosslinkable polyethylene or suitable equivalent plastic material has been used rather than heavy steel and certain advantages are derived from the use of the plastic material, such as, reduction in weight, easier and more effective cleaning of the drum and substantial reduction in labor intensive removal of hardened concrete which, when bonded to the interior of a steel mixing drum, requires extensive effort and time to remove.
The following U.S. patents relate to the construction of concrete mixers of the type in which the mixing drum rotates about a generally vertical or inclined longitudinal axis during the mixing operation and is tiltable or pivotal to a dumping position or disclose mixing drums constructed of plastic material:
U.S. Pat. No. 3,473,789 PA1 U.S. Pat. No. 4,435,082 PA1 U.S. Pat. No. 4,491,415 PA1 U.S. Pat. No. 4,569,648 PA1 U.S. Pat. No. 4,750,840 PA1 U.S. Pat. No. 4,756,623 PA1 U.S. Pat. No. 4,877,327 PA1 U.S. Pat. No. Re: 34,505 PA1 U.S. Pat. No. 5,118,198
U.S. Pat. No. 5,118,198 and the prior art listed and discussed therein, which is incorporated herein by reference thereto, discloses a cement mixer having a polyethylene mixing drum supported by a rigid cradle including radial support bars or braces under the bottom of the drum and four upright cradle arms that are attached to the polyethylene drum and a ring gear or bull gear by bolts extending through the gear, upper ends of the arms and the peripheral wall of the polyethylene mixing drum. The cradle is rotatably supported by a pivotal yoke supported from a frame. However, the prior patents listed above do not disclose concrete mixers which offers the same advantages in construction and design as achieved by the mixer of the present invention.